Flow testing at the Wressle oil site in Lincolnshire
Guest post by Kathryn McWhirter
Tomorrow (11 January 2017), North Lincolnshire Council is expected to decide on a plans for oil production at Egdon’s site at Wressle, near Scunthorpe.
The application includes proposals for the little-discussed process of acidisation.
In this Guest Post, writer and campaigner Kathryn McWhirter investigates the use of acid in the onshore oil and gas industry.
The first part of her post is an introduction to the process. If you want to read more, Kathryn McWhirter has made a detailed study based on scientific papers, industry training manuals, promotional literature for new, patented technologies, and discussions with engineers, geologists and scientists.
It’s time to talk about acid
Finally, we’re all talking about shale gas and fracking.
And we are ignoring the threat quietly posed by other extreme forms of gas and oil exploration. It’s time to broaden the discussion, and talk also about acidising, or acidisation.
Acidising, little understood outside the oil and gas industry, is coming to communities from Sussex and Surrey to Lincolnshire. Acidising poses its own threats, and is likely to lead on to fracking at a later stage.
Planners and councillors are already facing decisions on applications for acidisation, yet they don’t, for the most part, understand the science and the risks, nor the likelihood of proliferation – the very large number of wells that could be drilled.
The oil and gas industry seems to do its best to confuse, using obscure wording in planning applications. Planning applications may not mention acidising by name. ‘Well stimulation’ sounds relatively friendly. The application at Markwells Wood in Sussex by UK Oil and Gas Investments plc calls it:
‘a new non-massive fracking-based reservoir stimulation technology that does not involve massive hydraulic fracturing’.
Few studies have addressed the potential problems. In the UK there is little regulation or oversight.
Fracking is for shale. Acids are used to dissolve unyielding limestone or sandstone to make pathways for oil or gas flow. It’s not new. But like fracking, acidisation is now planned on a far bigger scale, down long, horizontal wells, a great multiplicity of wells. Many co-additives are needed to make the acids work effectively – a greater concentration of chemicals than are used in fracking fluids for shale.
Acids in question range from hydrochloric (for limestone) to the super-dangerous hydrofluoric (for sandstone). Acidising can be done at low pressure, or, like fracking shale, at major pressure that fractures rock. Not so long ago this would have been called an ‘acid frack’, but the government re-defined fracking in 2015 on the basis of the amount of fluid used rather than rock-cracking pressure.
If it’s not officially fracking, none of the new rules and regulations developed by government under oil and gas industry guidance will apply – so oil companies will feel free to drill and acidise in National Parks, Sites of Special Scientific Interest, Areas of Outstanding Natural Beauty and so on, at depths of less than 1,000 metres, without any of the baseline monitoring prescribed for fracking.
‘Acid fracking’ is not the only expression government and industry are keen to avoid in their attempt to make this extreme form of oil and gas extraction a non-issue for public, planners and press.
Conventional versus unconventional
There is also a game of words around the terms ‘conventional’ and ‘unconventional’. There are no statutory definitions for these terms. Geologists and engineers use the term ‘conventional’ to describe a geological formation from which oil or gas flows easily. ‘Conventional’ formations are permeable, so that one well can drain the rocks over a wide area.
In ‘unconventional’ formations, the oil or gas remains trapped in minute globules in the rock until ‘stimulated’ or released, by fracking, acidising or other means. ‘Unconventional’ formations are also known as ‘tight’ formations. At Balcombe and Horse Hill, for example, in Sussex and Surrey, the micrite limestone is ‘tight’ and ‘unconventional’.
Yet the government declared all the PEDLs across the Weald to be ‘conventional’ when the announcement of the 14th round of new petroleum exploration and development licences was buried in the Christmas wrapping paper of 2015. Meanwhile, oil and gas companies call their ‘prospects’ in the Weald ‘unconventional’ when talking to potential shareholders, but imply that they are ‘conventional’ when speaking to local communities.
Arguments against acidisation
Most of the negative arguments against fracking can also be made against acidisation – plus many more for ‘stimulation’ with hydrofluoric acid, one of the earth’s most dangerous chemicals.
UKOG CEO Stephen Sanderson has explained to shareholders that acidised wells would, like high-volume hydraulically fracked wells, need to be ‘back to back’ at regular intervals across the Weald to access as much as possible of the oil – since the oil will flow only from the ‘stimulated’ parts of the rock near the wellbore. This proliferation of wells, industrialisation of the countryside, is one of the main reasons to oppose unconventional drilling.
As with fracking for shale gas, there are questions over human and animal health, environment and climate.
Chemical use is even greater in acidisation than in hydraulic fracking. Solid and liquid waste will be toxic, highly saline and radioactive, a risk to groundwater, surface water and soil should accidents occur.
There will be potential air pollution from flares, potential groundwater pollution via faults, fractures and the well bore, noise and light pollution, traffic, the risk of spills and other accidents. Storm and floodwater may spread pollution. Wells may be acidised repeatedly. There is little research on the subject of repeated acidisation and the cumulative effect on our environment and human health. On-site workers and local communities are particularly at risk. Significantly, Portsmouth Water, the CPRE and the local Environment Agency objected to UKOG’s application to drill and acidise at Markwells Wood, West Sussex.
Fracking seemed enough to get our heads around. But the general public, campaigners, planners, water companies, politicians and regulators now all need to put acid on their agenda.
They should also think critically ahead and understand that, although initial planning applications may seek to acidise at below fracturing pressure, production stage will almost certainly require acidisation at pressure sufficient to fracture the rock.
Link to detailed study
To find out more, Kathryn McWhirter has carried out a detailed study of acidising. It is based on scientific papers, industry training manuals, promotional literature for new, patented technologies, and discussions with engineers, geologists and scientists.
Categories: guest post
DRILL OR DROP? 
The trouble is that Karen has approached this from the point of view that this is a ‘threat’. It really is not. Its deep, and the acids, although needing careful handling on the surface, immediately become spent. I put 10% acid on my patio and flush it straight onto grass. It doesnt bother it as its all reacted. Even if there were there is no mechanism to drive the water up against the force of gravity.
Karen seems to have the idea that this could impact human health. How? The reactants are required to be non hazardous, its in the Environmental Permitting Regulartions 2010. There will be more detail on this when Ruth publishes my detailed points that meant the ASA rejected the FoE science.
Horse Hill was naturally fractured. A flow rate of 1600bbls a day naturally means it doesnt need fracking! A bit of acid is always good to clean out the formation near the perforations.
Paul Tresto, you have worked with this for decades. Your comments would be welcome.
This is the realm of engineers and geologists I am afraid. Public opinion doesnt decide the laws of physics after all
Thank you Kathryn for your post.
Yet again we see the industry trying to play down serious issues.
Another hilarious classic,
‘a new non-massive fracking-based reservoir stimulation technology that does not involve massive hydraulic fracturing’.
We had a non-minuscule laugh about that sentence.
The alteration of the 1998 petroleum act is a clear indicator that the Government is aware of the dangers of unconventional oil and gas but chooses to alter long standing legislation to keep them off the hook.
The Preese Hall well failings prompted the DECC to suspend operations.
Recommendations by the British Geological Survey were made for future fracking operations
Preese Hall used only 8,400 cubic metres of fluid in total. Altering the infrastructure act to read that if you use less than 10,000 cubic metres in total now means you are not fracking. A future development the same as Preese Hall would not now be classed as a fracking application, therefore avoiding fracking guidelines and can be carried out in areas of outstanding natural beauty.
Of course to keep options open if the max total volume needs to be exceeded their get out is to use less than 1,000 cubic metres per stage. Acid use and high powered perforations would help to keep the volume down. Also the SoS can override if needed.
The changes to the 2015 infrastructure act
(a)a condition which prohibits associated hydraulic fracturing from taking place in land at a depth of less than 1000 metres; and
(b)a condition which prohibits associated hydraulic fracturing from taking place in land at a depth of 1000 metres or more unless the licensee has the Secretary of State’s consent for it to take place (a “hydraulic fracturing consent”).
(1)“Associated hydraulic fracturing” means hydraulic fracturing of shale or strata encased in shale which—
(a)is carried out in connection with the use of the relevant well to search or bore for or get petroleum, and
(b)involves, or is expected to involve, the injection of—
(i)more than 1,000 cubic metres of fluid at each stage, or expected stage, of the hydraulic fracturing, or
(ii)more than 10,000 cubic metres of fluid in total.
It is exactly this kind of nonsense by the industry and the government that enrages the public and produces more opposed to this unnecessary dangerous industry.
Quote ‘Chemical use is even greater in acidisation than in hydraulic fracking. Solid and liquid waste will be toxic, highly saline and radioactive, a risk to groundwater, surface water and soil should accidents occur.
There will be potential air pollution from flares, potential groundwater pollution via faults, fractures and the well bore, noise and light pollution, traffic, the risk of spills and other accidents. Storm and floodwater may spread pollution.’ end quote
That is staright out of the antifracking manual. The Environment Agency will have to approve every plan and issue a licence after evaluating risks to groundwater. The regulations that cover most of this including fluid disposal were published in August 2016. https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/545924/LIT_10495.pdf
So concentrated HCL, strong enough to cut through rocks, is safe? I’;d have thought that no matter how far down, it’s in the earth and will remain there doing its damage. What 10% acid do you use on your patio, Ken? Isn’t it formulated to inactivate rapidly? You say 10% – what strength is the acid used for oil extraction?
I’m speaking from ignorance here, so would be grateful for the information.
I have grandchildren and am thinking of what sort of earth we are leaving for them with nuclear waste, acid deposits etc.
Pat – you have about 1% HCl acid in your gastric acid in your stomach. The water treatment industry uses HCl at concentrations >20% as does the oil and gas industry. An acid fracture stimulation will use 28% HCl, an acid wash will use a lower concentration. The main uses of hydrochloric acid include the production of fertilizers, dyes and electroplating. Hydrochloric acid is also utilized in the production of rubber products and textiles. One of the most important uses of hydrochloric acid is the pickling of steel.
Click to access HYDROCHLORIC-ACID-28-PERCENT-TECH-MSDS.pdf
Ken’s patio cleaner is a low cost diluted version of the real thing: Hydrochloric Acid 28% – Brick & Patio Cleaner
http://www.bonnymans.co.uk/products/product.php?productID=6241
More obfuscation and ‘blurring’ of language and procedures to facilitate the frackers in their planning applications, how can any planning committee make an objective, properly considered decision on ‘flaky’ information? This just gets worse.
An excellent informative article from someone who knows what she is talking about and gives a link to a detailed study. Important information for the rest of us. There is simply no rational ground for using these unpredictable technologies when the clock is ticking on climate change (literally) see http://www.fastcoexist.com/3066994/one-year-from-today-well-have-blown-the-worlds-entire-carbon-budget and we do not need new sources of fossil fuels to make the transition to a low carbon economy, see the global and UK figures mapped out by The Solutions Project for transition to 100% renewables by 2050 http://thesolutionsproject.org/resources/ and the Energy [R]evolution 2015 scenario for transition to 2050 with different energy mix http://www.greenpeace.org/international/en/publications/Campaign-reports/Climate-Reports/Energy-Revolution-2015/. If you want to get a good firm grip of the whole ‘fracking’ ‘extreme fossil fuel extraction’ push from it’s earliest history give yourself 2 hours to watch the deeply informed presentation by long term Canadian investigative journalist https://thetyee.ca/Tyeenews/2016/02/08/Evening-With-Andrew-Nikiforuk/
It’s not actually an “excellent article” and I’m sorry to say she has a very poor technical understanding of acid jobs.
What is correctly stated in her larger paper, is that the acid wash is going to penetrate a few metres. (This has somehow been missed in the abbreviated paper posted above)
Quote:
‘Matrix’ means the environment close to the well. It is done at low or lowish pressure (below the pressure at which that particular geological location or ‘formation’ would fracture – this will vary depending on local conditions). The acid solution would typically penetrate between 1 and 5ft (30 to 150cm) into the surrounding rock, but sometimes in carbonate-rich rock it could travel 20ft (around 6m), creating small channels known as ‘wormholes’.
Higher concentrations of acid are used for matrix acidising than for acid washing or an acid frack – the solution would typically contain 18 per cent of chemicals, 15 per cent of which would be acid. Sandstone is much harder to dissolve, and matrix acidising of sandstone would affect a smaller diameter from the well , maybe 1 to 2ft (0.3 to 0.6 of a metre). In sandstone, the plan may be to dissolve particles of clay, feldspar or quartz within the sandstone to make or improve pathways for oil or gas.”
Acidisation has been used for years and is certainly not an unpredictable technology.
Mr Wilkinson, I would politely point out the author’s name is Kathryn not Karen.
When one reads about the scale of the unconventional industry, the methods employed, including all the toxins associated with production, the impacts on communities – one has to ask the question why we are extracting “tight” gas and oil onshore?
Without CCS it has been acknowledged by the CCC and the Royal Academy we should not be burning gas for energy beyond 2030. Yet it would take this industry a decade to become established. There are sufficient conventional supplies available to provide fossil fuels until we are able to transition to a carbon zero economy.
Understandably, many people legitimately ask why are we taking these risks in a densely populated country and against the wishes of communities.
I do not hold with the idea of trading with oil/gas producing nations has suddenly put us at risk. We have traded with these nations for many decades and have always been subject to the OPEC cartel. Indeed we sell weapons to the Saudi’s.
My view is we should continue to use conventional oil and gas for the shortest possible time – import what we need and keep unconventional reserves in the ground. Then we wouldn’t even be having these conversations about all the risks and impacts this industry undoubtedly brings.
The green energy technologies will mature and faster than the fossil fuel industry cares to admit. And once we are no longer dependent on fossil fuels – that is when we will have true energy security.
I am not a scientist or engineer but have followed the fracking controversy and still find it hard to understand why we are perpetuating the fossil fuel industry when climate change and the need to cut CO2 emissions absolutely means we must terminate this outdated industry driven by profit & greed.
Renewables are proving more and more each day that they are a more than viable non CO2 emitting alternative to meeting our energy needs – Engineers put your time, effort and money into developing them more, instead of this polluting, byproduct ridden fracking/acidisation junk.
Brian – what gets worse? The above article is written by an anti who lives near an oil well and supported by the “Engineer” Mike Hill, Professor Lawrence Dunne (I can’t say on this BB where he lives but you can google it), Emeritus Professor David Smythe (need I say anymore?). I didn’t bother checking the others but I expect they started from an anti position. The reason laterals were only acidised from the 1990’s is because the technology to drill laterals was only viable from the 1990’s.
Broadbench-2 (renamed to Kimmeridge-1) was drilled and acidised in 1959 (twice).
Ken – mycomments are as would be expected, this is another attempt to get oil and gas drilling stopped by an anti who lives somewhere near an O & G well. Wells in the south of England have been acidised many times, including in Hampshire where I worked in mid 80’s.
I also don’t understand the comment “Chemical use is even greater in acidisation than in hydraulic fracking. Solid and liquid waste will be toxic, highly saline and radioactive, a risk to groundwater, surface water and soil should accidents occur.”
My septic tank (along with millions of others) is toxic and a risk to ground water, surface water and soil “should accidents occur”…..
But lets not let reality get in the way of a good anti story! Did you know that a lot of potable water wells are acidised?
The EA decides which chemicals can be used and what happens to the spent acid – not the author of this article.
Hydrofluoric (HF) acid, one of the strongest inorganic acids, is used mainly for industrial purposes (eg, glass etching, metal cleaning, electronics manufacturing). Hydrofluoric acid also may be found in home rust removers. Exposure usually is unintentional and often is due to inadequate use of protective measures.
The article is correct in that HF needs to be treated with respect and handled carefully. I have used it many times in “mud acid” to clean out mud filtrate damage / clays from the near wellbore to improve PI. I don’t recall anyone getting injured through handling HF (or from up to 28% HCl which I have used in very large volumes). But I expect there will have been cases in the O & G industry as well as in all the other industries which use it.
With regard to “repeated acidisation”, I have not come across this before. The acid jobs I managed were large HCl for fractured limestone reservoirs and HF and Acetic for near wellbore clean up in sandstones.
There is probably more acid in a case of wine than in an equivalent volume of acid flow back…. But we all drink the wine don’t we?? Some of the same acids (Citric for example) are used in the wine making process, HCl is also used. Why do I mention wine?
Well said Paul. I could not see Kathryns post as I was on flaky wifi on a plane. I read it now, and surely she must have picked up that its been used for decades, with no real issues, on almost every well, including water wells, and the only issues are handling. That is never a reason to stop something. Its why protective clothing/gloves/glasses and safe handling systems are developed, under guidance from the HSE and EA . Dozens of industries use nasty chemicals, farming and almost any type of manufacturing.
Why all this mindless non scientific propaganda from someone who has applied little science and NO experience to the matter. Best left to the experts at the Environment Agency, as they are scientists and they deal with matters like this every day, and they can advise the councillors.
Cue an article about explosive perforators….
why do you bother with all this ken, you’ve won, fracking is going ahead, all you have to do is sit back and watch your gas bill get less and less, even if all goes wrong it won’t affect you as you don’t live in the desolate north
You guys talk a good fight (Ken, Paul). Some might even fall for the way the term ‘scientific’ get used and abused here (I look forward to responding to your ASA letter Ken). I’m just glad some people are digging more deeply. Perhaps Paul you could say why they go to such lengths in the States to get all flowback waste buried far and away from any possible contact with ground water systems, why farmers are not able to get insurance against well water pollution in fracked areas (if the risks are so low) or why so many animal deaths have been reported in its connection? USA: http://investigations.nbcnews.com/_news/2012/11/29/15547283-livestock-falling-ill-in-fracking-regions
2nd item – a UK farmer questions the insurance and other issues: https://www.youtube.com/watch?v=eX0ftC1XAZA
Hi Philip P – I think I mentioned before I don’t look at the stuff out of the US. Farmers in the UK are mostly hypocrites. They are the main polluters of our surface water, ground water, rivers, insects including our pollinators. They should get their own house in order before they start moaning (common past time for farmers) about other industries.
Hi Paul. Clearly you don’t want to consider any evidence.
Following up on your snidey swipes about Mike Hill “engineer” and Prof Lawrence Dunne (“need I say more”), and given that they may not be aware of these comments to put their views… for the sake of balance I’m adding their voices here:
Lawrence Dunne gives an interesting interview here: https://www.youtube.com/watch?v=nF9V8yw_ONo
Mike Hill appears in this doc briefly at 2m20s and more at length from 4m20s: https://www.youtube.com/watch?v=Ko27wj1Q-BQ
Philip, as I have said previously, I prefer to “consider” direct experience, not hearsay and Google. It would be interesting to know how much direct experience with Oil and Gas wells the various contributors to the article have.
I see we are both getting in trouble with moderator Paul today but I hope this restructured comment is deemed acceptable as it is an important issue, to me at least.
Ah then we need to look at evidence from further afield then. Any experience of multi stage million plus gallon 15000psi frack wells staged on clustered pad sites Paul? I don’t think any have been done in the UK yet have they?
This is quite an interesting post from Kathryn, whom I met in Parliament a couple of years ago when I, along with my fellow co-founders, launched the Onshore Energy Services Group – the trade association that represents the interests of small British supply chain companies in onshore oil and gas.
She was clearly dead against shale, but reasonable and those of us that took the time to speak to her found her very pleasant.
AFAIK, the use of dilute mineral acids like Hydrochloric Acid to remove drilling debris around the wellbore and stimulate the initial flow of oil or gas in soft, “claggy” sandstone, limestone and compacted clay reservoirs is not new and has been practiced all over the world without incident, so I’m not quite sure why Kathryn would now view it as a problem?
The acid solutions react with the alkaline rocks down there as they dissolve them, and are effectively neutralised yielding non-harmful residues of water, calcium salts (calcium chloride in the case of HCl and calcium fluoride in the case of HF) and a bit of CO2. This is why they are deemed acceptable for use because they are non-hazardous to groundwater given that they rapidly “degrade” (for want of a better description) to a safe state when used in this application and, if returned up the well with the oil or gas, will pose no particular disposal problem that I can see either.
They’re also used in relatively dilute form, and at depth – far away from the public and with no obvious or immediate pathway to connect them.
The people at greatest risk are the workers that handle these substances at the surface, but the COSHH Regulations apply and they should have all the necessary working practices and systems in place to facilitate their safe handling.
“Everything you need to know about the world economy”-capitalism is evil!
I used to sell 20 tonne bulk loads of acids to be added to animal feed. The hazard classification of these materials were horrendous (when taken out of context), but when used correctly and controlled were not only safe but extremely beneficial. How is bread kept from going mouldy in many countries, and killing the population via mycotoxins?
I am just as worried about the “hazard” posed by explosive gas and black liquid under my house, which could contaminate my water supply and then dramatically reduce the value of my property. (Anyone like to send a few quid to help me educate a few people of this information?)Quite irresponsible if my local council does not organise to get the GAS and OIL extracted before it has a chance to create such a perfect storm. Can’t understand why this major risk to the environment has been allowed to continue in situ so long. These materials have been known to be hazardous for many years, they should have been pumped out and made safe long ago. Absolute disgrace!
I’ve previously said to stop diluting the fight against fracking or you will lose even more credibility overnight. Attacking a safe and well practiced method is only going to undermine your cause even further.
This article demonstrates that the guardians of everything green and sacred don’t understand even the basics hence why I don’t listen to them anymore.
Wressle will 100% get the go ahead whether it be tomorrow or after a small tactical delay via the council.